Commitments and Contingencies - Payment Guarantees to Third Parties (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2019 USD ($)
Guarantee Obligations [Line Items]
Product warranty term	2 years
Payment Guarantee
Guarantee Obligations [Line Items]
Guarantor obligations	$ 64,172
Dasan Network Solutions, Inc. (DNS) | Payment Guarantee
Guarantee Obligations [Line Items]
DNI ownership interest	44.40%
Dasan Network Solutions, Inc. (DNS) | Payment Guarantee | Credit facility from Industrial Bank of Korea
Guarantee Obligations [Line Items]
Guarantor obligations	$ 8,400
Dasan Network Solutions, Inc. (DNS) | Payment Guarantee | Purchasing Card from Industrial Bank of Korea
Guarantee Obligations [Line Items]
Guarantor obligations	1,998
Dasan Network Solutions, Inc. (DNS) | Payment Guarantee | Korea Development Bank, Credit facility
Guarantee Obligations [Line Items]
Guarantor obligations	8,400
Dasan Network Solutions, Inc. (DNS) | Payment Guarantee | Korea Development Bank, General loan
Guarantee Obligations [Line Items]
Guarantor obligations	4,995
Dasan Network Solutions, Inc. (DNS) | Payment Guarantee | NongHyup Bank, Credit facility
Guarantee Obligations [Line Items]
Guarantor obligations	6,000
Dasan Network Solutions, Inc. (DNS) | Payment Guarantee | Borrowings from Korea Development Bank
Guarantee Obligations [Line Items]
Guarantor obligations	3,566
Dasan Network Solutions, Inc. (DNS) | Payment Guarantee | Payment Guarantee from Shinhan Bank
Guarantee Obligations [Line Items]
Guarantor obligations	3,000
Dasan Network Solutions, Inc. (DNS) | Payment Guarantee | Shinhan Bank, General Loan
Guarantee Obligations [Line Items]
Guarantor obligations	1,598
PNC Bank | Payment Guarantee
Guarantee Obligations [Line Items]
Guarantor obligations	4,550
Seoul Guarantee Insurance Co. | Payment Guarantee
Guarantee Obligations [Line Items]
Guarantor obligations	5,516
Industrial Bank of Korea | Payment Guarantee
Guarantee Obligations [Line Items]
Guarantor obligations	1,010
Industrial Bank of Korea | Payment Guarantee | Letter of Credit
Guarantee Obligations [Line Items]
Guarantor obligations	1,096
Korea Development Bank | Payment Guarantee
Guarantee Obligations [Line Items]
Guarantor obligations	6,908
NongHyup Bank | Payment Guarantee
Guarantee Obligations [Line Items]
Guarantor obligations	3,596
Woori Bank | Payment Guarantee
Guarantee Obligations [Line Items]
Guarantor obligations	1,932
Shinhan Bank | Payment Guarantee
Guarantee Obligations [Line Items]
Guarantor obligations	683
Shinhan Bank | Payment Guarantee | Purchasing Card
Guarantee Obligations [Line Items]
Guarantor obligations	573
AXA Insurance Company | Payment Guarantee
Guarantee Obligations [Line Items]
Guarantor obligations	175
Polska Agencja Zeglugi Powietrznej | Payment Guarantee
Guarantee Obligations [Line Items]
Guarantor obligations	112
DDE 64 LTD | Payment Guarantee
Guarantee Obligations [Line Items]
Guarantor obligations	$ 64